My conception of the "missile platform in carrier" idea was this:
A 6kton ship with many hangar bays, engines, whatever.
A second 'ship' inside the first 6kton ship's hangars (made to fit exactly) would have no engines or fuel, minimal maintenance, no armour or shields.
This 2nd 'ship' is really just a box launcher missile platform. All box launchers, a few missile firecons, crew quarters for the fire cons and that's it.
This is meant to use the lowered space requirements of box launchers. (0.15x size + 0.05 for hangar inefficiency = 0.20x which is smaller than 0.25x reduction)
And obviously generates an incredibly huge salvo size.
The trade off is more complex logistics (two types of shipyards and two ships to train) and increased reload times when using smaller missiles/higher tech. Hangar reload doesn't improve with technology and with small missiles (eg. size 3), you can eventually get 25% launchers that reload as fast as hangars in which case you may as well build 6kton ships with 25% launchers.